Following natural disasters, it is often necessary to provide emergency shelters, for example housing. Such shelters are usually provided by canvas tents but such tents are not particularly sturdy and are inadequate for extreme weather and temperature conditions often encountered at times of emergency. Furthermore, shelter is often required for an extended period of time in such circumstances and canvas tents can wear out before the need for them has been superseded by the building of permanent shelters. Also, canvas tents are unsuitable for some uses, such as field hospitals and stores, since it is difficult to set up hygienic conditions within a canvas tent, militating against their use as a field hospital; also canvas tents are easily accessed, making them easy to loot if valuable stores are held within them.
Large shelters for food and equipment storage are made from large metal frames covered with flexible impermeable material. These are difficult to construct and often require prepared foundations.
It is known to form buildings by inflating a skin pneumatically an pouring concrete over the inflated skin (see U.S. Pat. No. 2,270,229, U.S. Pat. No. 3,734,670, GB-1242647, U.S. Pat. No. 4,746,471, GB-603655) or by applying a layer of liquid concrete onto a skin that can be inflated (see U.S. Pat. No. 3,462,521 and U.S. Pat. No. 4,170,093).
However, such arrangements are time consuming and technically difficult to construct and so are not suitable for use in disaster areas. They will also generally require the deployment of more than one person in order to erect the building and shelter. Also, such shelters often cannot be erected in an emergency area since concrete mixing on a substantial scale requires heavy machinery and power on a scale that is not necessarily available. Also any concrete that has been mixed must be used before it sets, which imposes a timescale for building the shelters that might not be achievable.
U.S. Pat. No. 3,292,338 describes a method of constructing a building by inflating a bag, applying foamed resin blocks to the inside of the bag to form an igloo-like structure that provides the strength of the building, and finally an interior lining is applied. This building requires a substantial amount of work to construct.
U.S. Pat. No. 4,446,083 describes an air-inflated concrete shell suitable for forming the roof of a building. In order to make a roof using this technique, a substantial framework is constructed and an earth support bank is built within the framework. A layer of reinforcing fabric is then spread over the framework to form a covering and it attached to the framework. Dry mortar is then spread over the reinforcing fabric and further alternating layers of fabric and mortar are then applied. Air is pumped under the fabric layers, which inflates the roof in a domed shape. The mortar is then densified by vibrating the perimeter of the shell to work the mortar into the fabric layers and water is sprayed onto the shell and left to set. After setting, the roof is raised, walls are constructed and the roof is then lowered onto the walls. The building of the framework and the earth support bank is time consuming and labour intensive and is completely unsuited for the quick construction of shelters in emergency areas.